A b-microalloyed fe-mn-co-cr system metastable high-entropy alloy and additive manufacturing technology forming method

Abstract

This invention discloses a B-microalloyed Fe-Mn-Co-Cr metastable high-entropy alloy and its forming method using additive manufacturing technology, belonging to the field of high-entropy alloys. The chemical formula of the B-microalloyed Fe-Mn-Co-Cr metastable high-entropy alloy is Fe. a Mn b Co c Cr c B d The atomic percentages are a = 40–50, b = 30–40, c = 8–10, and d = 0.03–1, with a + b + 2c + d = 100. The high-entropy alloy is a single-phase FCC. The B-microalloyed Fe-Mn-Co-Cr metastable high-entropy alloy is prepared by additive manufacturing. During additive manufacturing, different process parameters are selected according to the particle size range of the pre-alloyed powder. The printed product obtained by this invention has a tensile strength of up to 800–805 MPa, a yield strength of 500–510 MPa, and an elongation of 43–45%. This invention has a reasonable component design, a simple and controllable preparation process, and produces a product with excellent performance, facilitating large-scale industrial application.

Description

Technical Field

[0001] This invention discloses a B microalloyed Fe-Mn-Co-Cr metastable high-entropy alloy and its forming method using additive manufacturing technology, belonging to the field of high-entropy alloys. Background Technology

[0002] FeMnCoCr metastable high-entropy alloys have attracted much attention in the field of structural materials research due to their excellent mechanical properties, and have great application potential in cryogenic hydrogen-contaminated structural components in fields such as hydrogen energy storage and transportation, and aerospace. The FeMnCoCr metastable dual-phase high-entropy alloy system was first proposed in 2016 by Li Zhiming of Central South University. This type of metastable high-entropy alloy system exhibits excellent plasticity, high strength, and high work hardening rate due to the synergistic effect of dislocation-twin / phase transformation-induced plasticity enhancement during deformation, the alternation of dislocation-twin / phase transformation, and the dynamic Hall-Page effect caused by numerous nano-deformation twins in the martensite phase. It is noteworthy that existing metastable high-entropy alloy composition designs mainly focus on the intermetallic elements Fe and Mn, while designs using non-metallic elements for interstitial reinforcement are rarely reported.

[0003] Currently published patents also involve high-strength and high-toughness metastable dual-phase FeMnCrCo high-entropy alloys. For example, application number 202211039432.4 describes a metastable dual-phase FeMnCrCo high-entropy alloy and its preparation method. The metastable dual-phase Fe... a Mn b Cr c Co d This is a high-entropy alloy composed of Fe, Mn, Cr, and Co elements, where a, b, c, and d represent the atomic percentages of the alloying elements, wherein 36 ≥ b ≥ 31, 10 ≥ c ≥ 9, 9 ≥ d ≥ 8, 52 ≥ a ≥ 45, and a + b + c + d = 100. Through casting, rolling, and heat treatment, a product with high strength and good elongation is obtained. In this patented embodiment, the elongation of the product is 10-23%.

[0004] The search revealed that, to date, there are few reports on the introduction of boron into FeMnCrCo high-entropy alloys, and in particular, no reports on the preparation of boron-containing FeMnCrCo high-entropy alloys using direct energy deposition technology. Summary of the Invention

[0005] This invention is the first to introduce an appropriate amount of boron into a FeMnCrCo high-entropy alloy, resulting in a product with superior strength and extremely high elongation. Simultaneously, this invention also pioneered a matching direct energy deposition (DED) forming method and optimized the range of process parameters.

[0006] This invention discloses a B-microalloyed Fe-Mn-Co-Cr metastable high-entropy alloy, wherein the chemical formula of the B-microalloyed Fe-Mn-Co-Cr metastable high-entropy alloy is Fe. a Mn b Co c Cr c B d The atomic percentages are a = 40~50, b = 30~40, c = 8~10, d = 0.03~1, and a + b + 2c + d = 100; the phase of the high-entropy alloy is FCC single phase, and the high-entropy alloy is prepared by additive manufacturing technology.

[0007] Preferably, the present invention provides a B-microalloyed Fe-Mn-Co-Cr metastable high-entropy alloy, wherein the chemical formula of the B-microalloyed Fe-Mn-Co-Cr metastable high-entropy alloy is Fe. a Mn b Co c Cr c B d In terms of atomic percentages, a = 47~48.5, b = 31~33, c = 9~10, d = 0.05~1, and a + b + 2c + d = 100. That is, Fe a Mn b Co c Cr c B d The molar ratio of Fe, Mn, Co, Cr, and B is 47~48.5:31~33:9~10:9~10:0.05~1, and a+b+2c+d=100.

[0008] Preferably, the present invention provides a B-microalloyed Fe-Mn-Co-Cr metastable high-entropy alloy, wherein the chemical formula of the B-microalloyed Fe-Mn-Co-Cr metastable high-entropy alloy is (Fe a Mn b Co c Cr c ) e B d Where a=48, b=32, c=10, d=0.05~0.06, e=99~99.95, and (a+b+2c)×e%+d=100. That is, in the formula (Fe... a Mn b Co c Cr c ) e B d The molar ratio of Fe, Mn, Co, and Cr is a:b:c:c; the ratio of the total number of moles of Fe, Mn, Co, and Cr to the number of moles of B is e:d.

[0009] Preferably, the present invention provides a B-microalloyed Fe-Mn-Co-Cr metastable high-entropy alloy, wherein the chemical formula of the B-microalloyed Fe-Mn-Co-Cr metastable high-entropy alloy is (Fe 48 Mn 32 Co 10 Cr 10 ) 99.95 B 0.05 In the formula (Fe) 48 Mn 32 Co 10 Cr 10 ) 99.95 B 0.05 In this composition, the molar ratio of Fe, Mn, Co, and Cr is 48:32:10:10, and the ratio of the total moles of Fe, Mn, Co, and Cr to the moles of B is 99.95:0.05. Alternatively, the chemical formula of the B microalloyed Fe-Mn-Co-Cr metastable high-entropy alloy is (Fe... 48 Mn 32 Co 10 Cr 10 ) 99 B1. In the formula (Fe) 48 Mn 32 Co 10 Cr 10 ) 99 In B1, the molar ratio of Fe, Mn, Co, and Cr is 48:32:10:10, and the ratio of the total number of moles of Fe, Mn, Co, and Cr to the number of moles of B is 99:1.

[0010] This invention discloses a direct energy deposition forming method for B microalloyed Fe-Mn-Co-Cr metastable high-entropy alloys, comprising the following steps: using pre-alloyed powder prepared according to the designed composition as raw material, and obtaining the product through additive manufacturing process.

[0011] In this invention, when the particle size range of the raw material pre-alloyed powder is 53~120 μm and the D50 is 80~100 μm, preferably 83 μm, the additive manufacturing process adopted is as follows: a model of the part to be prepared is constructed using three-dimensional software, and the motion path of the robotic arm is designed according to the shape of the model; the part is deposited on a 316L substrate using direct energy deposition technology, using a Gaussian distributed laser light source, and both the powder feed and the protective gas are Ar gas; the direct energy deposition process parameters are set as follows: laser spot diameter 1~2 mm, substrate preheating temperature 100~150℃, protective gas flow rate 7~13 L / min, laser power 180~700 W, laser scanning speed 3~10 mm / s, single-pass overlap 40~50%, and Z-axis lift 0.4~0.5 mm.

[0012] As a preferred embodiment, in this invention, when the particle size range of the pre-alloyed raw material powder is 53~120 μm and the D50 is 80~100 μm, preferably 83 μm, the additive manufacturing process adopted is as follows: a model of the part to be prepared is constructed using three-dimensional software, and the motion path of the robotic arm is designed according to the shape of the model; the part is deposited on a 316L substrate using direct energy deposition technology, using a Gaussian distributed laser light source, and both the powder feed and the protective gas are Ar gas; the direct energy deposition process parameters are set as follows: laser spot diameter 1~2 mm, substrate preheating temperature 100~150℃, protective gas flow rate 7~9 L / min, laser power 190~360 W, laser scanning speed 4~8 mm / s, single-pass overlap 40~45%, and Z-axis lift 0.4~0.5 mm.

[0013] As a further preferred option, when the particle size range of the raw material pre-alloyed powder is 53~120 μm, and the D50 is 80~100 μm, preferably 83 μm, the laser power is 190~210W.

[0014] In this invention, when the particle size range of the raw material pre-alloyed powder is 15~53μm and the D50 is 30~40μm, preferably 36μm, a three-dimensional software is used to construct the part model to be prepared, and the movement path of the robotic arm is designed according to the shape of the model. The part is deposited on a 316L substrate by laser powder bed fusion deposition, using a Gaussian distributed laser light source, and both the powder feed and the protective gas are Ar gas. The laser powder bed fusion deposition process parameters are set as follows: laser spot diameter 40~100 mm, substrate preheating temperature 100~150℃, protective gas flow rate 7~13 L / min, laser power 150~250W, laser scanning speed 400~1000 mm / s, single-pass overlap 40~50%, and layer thickness 0.03~0.05 mm.

[0015] As a preferred embodiment, in this invention, when the particle size range of the pre-alloyed raw material powder is 15~53μm and the D50 is 30~40μm, preferably 36μm, a three-dimensional software is used to construct the part model to be prepared, and the motion path of the robotic arm is designed according to the shape of the model. The part is deposited on a 316L substrate by laser powder bed fusion deposition, using a Gaussian distributed laser light source, and both the powder feeding and protective gas are Ar gas. The laser powder bed fusion deposition process parameters are set as follows: laser spot diameter 40~60 mm, substrate preheating temperature 100~120℃, protective gas flow rate 7~9 L / min, laser power 190~210W, laser scanning speed 750~850mm / s, single-pass overlap 40~41%, and layer thickness 0.034~0.05 mm.

[0016] The B-microalloyed Fe-Mn-Co-Cr metastable high-entropy alloy designed and prepared in this invention exhibits a tensile strength of 600-805 MPa, a yield strength of 350-550 MPa, and an elongation of 25-50% in the printed state. After optimization, the tensile strength of the printed product is approximately 800-805 MPa, the yield strength is 500-510 MPa, and the elongation is approximately 43-45%.

[0017] The B microalloyed Fe-Mn-Co-Cr metastable high-entropy alloy designed and prepared in this invention has a density of ≥99% in the printed product.

[0018] Principles and advantages

[0019] In this invention, boron (B) is used as a microalloying dopant, and its effective doping amount is crucial. Therefore, this invention is the first to attempt and obtain an effective molar doping range of 0.05~1% (preferably 0.05~0.06%) for B. Combined with appropriate additive manufacturing process parameters, matching process parameters were developed for raw materials of different particle sizes, resulting in products with extremely high elongation and excellent strength. Simultaneously, through the composition design and matching of the preparation process parameters in this invention, crack-free, highly dense printed preforms were obtained, providing the necessary conditions for subsequently obtaining products with even superior performance.

[0020] In this invention, a suitable amount of boron (B) acts as an interstitial atom. Its interstitial position differs from non-metallic elements such as C / N. B not only tends to segregate to grain boundaries but also diffuses from the grain interior to the grain boundaries faster than oxygen (O), thus suppressing O segregation at grain boundaries due to B doping. Simultaneously, the large amount of charge accumulated around B enhances the interaction between B and metal atoms, strengthening grain boundary cohesion. Furthermore, a suitable amount of boron generates a significant grain boundary resistance effect, reducing the interface movement speed. Moreover, a suitable amount of B can lower the interface energy, reduce the capillary driving force of competitive grain coarsening, and decrease the resulting increase in GB cohesion, thereby effectively improving strength. Furthermore, B has no effect on matrix stacking fault energy or twinning nucleation mechanisms. The deformation of FCC structural materials is determined by the interplay between dislocation slip, twinning, and martensitic phase transformation mechanisms. The combined activation of multiple deformation mechanisms enables it to maintain stable work hardening capacity under high stress levels, which is the main reason for the excellent plasticity of FeMnCoCr alloys. This invention forms a FeMnCoCr high-entropy alloy with a stable FCC phase by controlling the process parameters of additive manufacturing, thereby improving strength while achieving high ductility. Attached Figure Description

[0021] Figure 1 This is a microscopic porosity characterization diagram of the printed sample obtained in Example 1;

[0022] Figure 2The images show the XRD patterns of the powder used in the embodiments of the present invention and the printed samples obtained in Example 1.

[0023] Figure 3 The graph shows the quasi-static tensile properties of the printed samples obtained in Examples 1-3 and Comparative Example 1.

[0024] Figure 4 The graph shows the quasi-static tensile properties of the printed samples obtained in Example 4 and Comparative Example 2.

[0025] Figure 5 This is a graph showing the quasi-static tensile properties test results of the printed sample obtained in Example 5;

[0026] Figure 6 The image shows the optical microscopic porosity characterization of the printed sample obtained in Comparative Example 3.

[0027] from Figure 1 It can be seen that the printed sample has high formability, no cracks or pores on the surface, and a high degree of densification.

[0028] from Figure 2 As can be seen, by controlling the printing process parameters, it is possible to form printed samples with a stable face-centered cubic (FCC phase) structure.

[0029] from Figure 3 The results show that when the boron doping content is within 0.05-1%, the samples exhibit excellent strength and ductility, with ductility values ​​of 49.32%, 44.64%, and 3.69%, respectively. In contrast, as a comparative example, when the boron doping content reaches 2%, the printed samples suffer significant ductility loss, reaching only 9.56%.

[0030] from Figure 4 As can be seen from this, as a comparative example, when the direct energy deposition printing process parameters are not within the expected range, it is impossible to form a high-strength and high-plasticity printed sample.

[0031] from Figure 5 As can be seen from the optimized laser powder bed fused deposition process parameters, the formed sample exhibits a tensile strength of 802.31 MPa, a yield strength of 507.49 MPa, and an elongation of 43.83%.

[0032] from Figure 6 As can be seen from the data, as a comparative example, when the laser powder bed fused deposition process parameters are not within the expected range, the formed sample surface has a lot of voids, making it impossible to form a high-strength and high-plasticity printed sample. Detailed Implementation

[0033] The technical solutions in the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that for those skilled in the art, various modifications and improvements (including other additive manufacturing technologies, different printing parameters, etc.) made without departing from the principle of the present invention should also be considered as falling within the protection scope of the present invention.

[0034] Example 1

[0035] A metastable high-entropy alloy based on the Fe-Mn-Co-Cr system, doped with boron, is prepared by weighing elemental raw materials of Fe, Mn, Co, and Cr with a purity ≥ 99.9 wt.% and ferroboron; using vacuum atomization technology, a alloy with the composition (Fe...) is prepared. 48 Mn 32 Co 10 Cr 10 ) 99.95 B 0.05 After spherical pre-alloying powder is formed, it is dried in a vacuum drying oven at 100 ℃ for 3 h. After furnace cooling, the powder with a particle size of 53-120 μm is sieved and added to the powder feeding cylinder of the direct energy deposition (DED) equipment. The DED equipment parameters are set as follows: laser spot diameter 1.5 mm, substrate preheating temperature 100 ℃, laser power 200 W, scanning speed 8 mm / s, Z-axis lift 0.45 mm, single-pass overlap 40%, Ar protective gas flow rate 8 L / min. The DED equipment is then turned on, and a laser serpentine reciprocating scan is performed with 90° interlayer rotation to form the original powder on a 316L stainless steel substrate until the forming is complete. A metastable high-entropy alloy (denoted as B0.05) based on the B-doped Fe-Mn-Co-Cr system is obtained.

[0036] The tensile strength of the obtained printed sample was 647.16 MPa, the yield strength was 332.84 MPa, the elongation was 49.32%, and the density was 99.61%.

[0037] Example 2

[0038] The composition of the spherical pre-alloyed powder prepared by vacuum atomization technology in Example 1 was changed to (Fe) 48 Mn 32 Co 10 Cr 10 ) 99.5 B 0.5 Afterwards, all other parameters were the same as in Example 1, and a high-entropy alloy sample (denoted as B0.5) was obtained. The tensile strength of the obtained printed sample was 673.31 MPa, the yield strength was 407.72 MPa, the elongation was 44.64%, and the density was 99.74%.

[0039] Example 3

[0040] The composition of the spherical pre-alloyed powder prepared by vacuum atomization technology in Example 1 was changed to (Fe) 48 Mn 32 Co 10 Cr 10 ) 99 Following B1, all other parameters remained the same as in Example 1, resulting in a high-entropy alloy sample (denoted as B1). The obtained printed sample exhibited a tensile strength of 704.34 MPa, a yield strength of 446.79 MPa, an elongation of 34.69%, and a density of 99.69%.

[0041] Comparative Example 1

[0042] When the boron doping content is further increased during the technical process, that is, the composition of the spherical pre-alloyed powder prepared by vacuum atomization technology in Example 1 is changed to (Fe 48 Mn 32 Co 10 Cr 10 ) 98 Following B2, all other parameters remained the same as in Example 1, resulting in a high-entropy alloy sample (denoted as B2). The obtained printed sample exhibited a tensile strength of 650.12 MPa, a yield strength of 463.06 MPa, and an elongation of only 9.56%; its density was 99.48%.

[0043] Comparative Example 2

[0044] A metastable high-entropy alloy based on the Fe-Mn-Co-Cr system, doped with boron, was prepared by modifying the process parameters of direct energy deposition. The raw materials consisted of elemental Fe, Mn, Co, and Cr with a purity ≥ 99.9 wt.%, along with ferroboron. The alloy was prepared using vacuum atomization technology. 48 Mn 32 Co 10 Cr 10 ) 99.95 B 0.05After spherical pre-alloying powder is formed, it is dried in a vacuum drying oven at 100 ℃ for 3 h. After furnace cooling, the powder with a particle size of 53-120 μm is sieved and added to the powder feed tank of the direct energy deposition (DED) equipment. The DED equipment parameters are set as follows: laser spot diameter 1.5 mm, substrate preheating temperature 100 ℃, laser power 150 W, scanning speed 4 mm / s, Z-axis lift 0.45 mm, single-pass overlap 40%, Ar protective gas flow rate 8 L / min. The DED equipment is then turned on, and a laser serpentine reciprocating scan is performed with 90° interlayer rotation to form the original powder on a 316L stainless steel substrate until the forming is complete. A metastable high-entropy alloy (denoted as B150-8) based on the B-doped Fe-Mn-Co-Cr system is obtained. The tensile strength of the obtained printed sample was 575.16 MPa, the yield strength was 294.89 MPa, the elongation was 17.25%, and the density was 98.65%.

[0045] Example 4

[0046] A metastable high-entropy alloy based on the boron-doped Fe-Mn-Co-Cr system was developed by modifying the process parameters of direct energy deposition (DAD). The process involved weighing elemental raw materials of Fe, Mn, Co, and Cr with a purity ≥99.9 wt.%, along with ferroboron. Spherical pre-alloyed powder with the composition (Fe48Mn32Co10Cr10)99.95B0.05 was prepared using vacuum atomization. The pre-alloyed powder was then dried in a vacuum oven at 100 ℃ for 3 h. After furnace cooling, the powder was sieved to a particle size of 53-120 μm and added to the powder feeding cylinder of the DAD equipment. The DAD equipment parameters were set as follows: laser spot diameter 1.5 mm, substrate preheating temperature 100 ℃, laser power 800 W, scanning speed 8 mm / s, Z-axis lift 0.45 mm, single-pass overlap 40%, and Ar protective gas flow rate 8. The laser speed was increased to L / min, and the direct energy deposition equipment was turned on. A serpentine laser scanning process was performed, with interlayer rotation of 90° to form the original powder onto a 316L stainless steel substrate until the forming process was complete. A metastable high-entropy alloy (denoted as B800-8) based on the B-doped Fe-Mn-Co-Cr system was obtained. The tensile strength of the obtained printed sample was 712.99 MPa, the yield strength was 364.19 MPa, the elongation was 15.89%, and the density was 98.41%. The elongation of the product obtained in this example was significantly lower than that of other examples.

[0047] Example 5

[0048] A metastable high-entropy alloy based on the Fe-Mn-Co-Cr system, doped with boron, is prepared by weighing elemental raw materials of Fe, Mn, Co, and Cr with a purity ≥ 99.9 wt.% and ferroboron; using vacuum atomization technology, a alloy with the composition (Fe...) is prepared. 48 Mn 32 Co 10 Cr 10 ) 99.95 B 0.05 After spherical pre-alloying powder is formed, it is dried in a vacuum drying oven at 100 ℃ for 3 h. After furnace cooling, the powder with a particle size of 15-53 μm is sieved and added to the powder feeding cylinder of a laser powder bed fused deposition (LDP) system. The LDP system parameters are set as follows: laser spot diameter 50 mm, substrate preheating temperature 100 ℃, laser power 200 W, scanning speed 800 mm / s, layer thickness 0.05 mm, single-pass overlap 40%, and Ar protective gas flow rate 8 L / min. The LDP system is then turned on, and laser strip scanning is performed with 90° rotation between layers to form the original powder onto a 316L stainless steel substrate until the forming is complete. A B-doped Fe-Mn-Co-Cr metastable high-entropy alloy (denoted as B-LPBF) formed by LDP technology is obtained. The tensile strength of the obtained printed sample was 802.31 MPa, the yield strength was 507.49 MPa, the elongation was 43.83%, and the density was 99.76%.

[0049] Comparative Example 3

[0050] As a comparative example, a metastable high-entropy alloy based on the B-doped Fe-Mn-Co-Cr system was prepared by altering the process parameters of laser powder bed fusion deposition. Metallic raw materials with a purity ≥99.9 wt.% (Fe, Mn, Co, Cr) and ferroboron were weighed. The alloy was prepared using vacuum atomization technology with a composition of (Fe... 48 Mn 32 Co 10 Cr 10 ) 99.95 B 0.05After spherical pre-alloying powder is formed, it is dried in a vacuum drying oven at 100 ℃ for 3 h. After furnace cooling, the powder with a particle size of 15-53 μm is sieved and added to the powder feeding cylinder of a laser powder bed fused deposition (LFD) system. The LFD system parameters are set as follows: laser spot diameter 50 mm, substrate preheating temperature 100 ℃, laser power 400 W, scanning speed 400 mm / s, layer thickness 0.05 mm, single-pass overlap 40%, and Ar protective gas flow rate 8 L / min. The LFD system is then started, and laser strip scanning is performed with 90° rotation between layers to form the original powder onto a 316L stainless steel substrate until the forming process is complete. A B-doped Fe-Mn-Co-Cr metastable high-entropy alloy formed by LFD technology is obtained. The printed sample exhibits overmelting, and many pores are observed under an optical microscope, indicating that high-density, high-performance samples cannot be formed under these printing parameters.

[0051] Comparative Example 4

[0052] A metastable high-entropy alloy based on the Fe-Mn-Co-Cr system without elemental dopant was prepared by weighing elemental raw materials of Fe, Mn, Co, and Cr with a purity ≥ 99.9 wt.% and using vacuum atomization technology to prepare an alloy with the composition Fe... 48 Mn 32 Co 10 Cr 10 After spherical pre-alloying powder is formed, it is dried in a vacuum drying oven at 100 ℃ for 3 h. After furnace cooling, the powder with a particle size of 53-120 μm is sieved and added to the powder feeding cylinder of a direct energy deposition (DED) system. The DED system parameters are set as follows: laser spot diameter 1.5 mm, substrate preheating temperature 100 ℃, laser power 300 W, scanning speed 6 mm / s, Z-axis lift 0.45 mm, single-pass overlap 40%, Ar protective gas flow rate 8 L / min. The DED system is then started, and a serpentine laser scanning motion is performed with 90° interlayer rotation to form the original powder onto a 316L stainless steel substrate until the forming process is complete. A metastable high-entropy alloy with no doped Fe-Mn-Co-Cr is obtained.

[0053] The obtained printed sample exhibited a tensile strength of 611.17 MPa, a yield strength of 300.21 MPa, and an elongation of 44.51%; its density was 99.73%. A comparison reveals that doping with trace amounts of boron (B) in Fe-Mn-Co-Cr metastable high-entropy alloys can achieve a synergistic improvement in both strength and ductility.

Claims

1. A B microalloyed Fe-Mn-Co-Cr based metastable high-entropy alloy, characterized in that: The chemical formula of the B-microalloyed Fe-Mn-Co-Cr metastable high-entropy alloy is Fe. a Mn b Co c Cr c B d The atomic percentages are a = 47~48.5, b = 31~33, c = 9~10, d = 0.05~1, and a + b + 2c + d = 100; the phase of the high-entropy alloy is FCC single phase, and the high-entropy alloy is prepared by additive manufacturing technology. The high-entropy alloy is prepared by additive manufacturing technology, including the following steps: using pre-alloyed powder prepared according to the designed composition as raw material, and obtaining the product through additive manufacturing process; When the particle size range of the pre-alloyed raw material powder is 53~120 μm and the D50 is 80~100 μm, the additive manufacturing process adopted is as follows: 3D software is used to construct the part model to be prepared, and the motion path of the robotic arm is designed according to the shape of the model; the part is deposited on a 316L substrate using direct energy deposition technology, using a Gaussian distributed laser light source, and both powder feeding and protective gas are Ar gas; the direct energy deposition process parameters are set as follows: laser spot diameter is 1~2 mm, substrate preheating temperature is 100~150℃, protective gas flow rate is 7~9 L / min, laser power is 190~360 W, laser scanning speed is 4~8 mm / s, single-pass overlap is 40~45%, and Z-axis lift is 0.4~0.5 mm; When the particle size range of the pre-alloyed raw material powder is 15~53μm and the D50 is 30~40μm, the required part model is constructed using 3D software, and the movement path of the robotic arm is designed according to the shape of the model. The part is deposited on a 316L substrate by laser powder bed fusion deposition, using a Gaussian distributed laser light source, and both the powder feed and the protective gas are Ar gas. The laser powder bed fusion deposition process parameters are set as follows: laser spot diameter 40~100 mm, substrate preheating temperature 100~150℃, protective gas flow rate 7~13 L / min, laser power 150~250W, laser scanning speed 400~1000 mm / s, single-pass overlap 40~50%, and layer thickness 0.03~0.05 mm.

2. The B-microalloyed Fe-Mn-Co-Cr metastable high-entropy alloy according to claim 1, characterized in that: The chemical formula of the B-microalloyed Fe-Mn-Co-Cr metastable high-entropy alloy is (Fe a Mn b Co c Cr c ) e B d , where a=48, b=32, c=10, d=0.05~1, e=99~99.95, and (a+b+2c)×e%+d=100. 3.The B micro-alloyed Fe-Mn-Co-Cr metastable high-entropy alloy according to claim 2, characterized in that: The chemical formula of the B microalloyed Fe-Mn-Co-Cr metastable high-entropy alloy is (Fe 48 Mn 32 Co 10 Cr 10 ) 99.95 B 0.05 In the chemical formula, the ratio of the total moles of Fe, Mn, Co, and Cr to the moles of B is 99.95:0.

05. Or the chemical formula of the B microalloyed Fe-Mn-Co-Cr metastable high-entropy alloy is (Fe 48 Mn 32 Co 10 Cr 10 ) 99 B1; In the chemical formula, the ratio of the total number of moles of Fe, Mn, Co, and Cr to the number of moles of B is 99:

1. 4.The B microalloyed Fe-Mn-Co-Cr system metastable high-entropy alloy of claim 1, wherein: When the particle size range of the raw material pre-alloyed powder is 53~120 μm and the D50 is 80~100 μm, the laser power is 190~210W.

5. The B-microalloyed Fe-Mn-Co-Cr metastable high-entropy alloy as described in claim 1, characterized in that: When the particle size range of the raw material pre-alloyed powder is 15~53μm and the D50 is 30~40μm, the laser powder bed fused deposition process parameters are set as follows: laser spot diameter 40~60 mm, substrate preheating temperature 100~120℃, protective gas flow rate 7~9 L / min, laser power 190~210W, laser scanning speed 600~1000 mm / s, single-pass overlap 40~45%, and layer thickness 0.034~0.05 mm.

6. The B-microalloyed Fe-Mn-Co-Cr metastable high-entropy alloy as described in any one of claims 1-4, characterized in that: The B microalloyed Fe-Mn-Co-Cr metastable high-entropy alloy has a tensile strength of 800~805MPa, a yield strength of 500~510MPa, and an elongation of 43~45% in the printed form.

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